Fuel injection device



sePt- 8, 1964 y J. H. HILL ETAL 3,147,594

FUEL INJECTION DEVICE Filed March 19, 1962 ,MKM

United States Patent O 3,147,594 FUEL INJECTIN DEVICE John H. Hill, Grosse Pointe, and Stuart W. Pond, St. Clair Shores, Mich., assignors to Continental Aviation and Engineering Corporation, Detroit, Mich., a corporation of Virginia Filed Mar. 19, 1962, Ser. No. 180,439 Claims. (Cl. oil-39.74)

This invention pertains to turbo-jet engines and particularly to a pyrophoric fueled afterburner to be utilized to augment thrust created by such an engine. More particularly this invention pertains to an annular fuel injection device for such an afterburner.

The rapidly expanding military requirements for missile evaluation and lighter aircraft crew training have created the need for continued improvements in operational target drone aircraft. Foremost among these needed improvements is increased engine thrust at high altitudes. Afterburners utilizing conventional hydrocarbon fuels have been developed to meet this need. This type of thrust augmenter, however, has several disadvantages which are either totally absent or greatly minimized when an afterburner employing pyrophoric fuels is utilized. Among these, hydrocarbon fuels are subject to combustion instability at high altitudes which often causes flameouts. This phenomena does not occur with pyrophoric fuels. Further, pyrophoric fuels ignite upon contact with air. This means that the need for complex ignition systems, which are expensive and which often lead to malfunction, is dispensed with. Pyrophoric fuels then can provide the means for a simple, inexpensive afterburner which can be constructed to replace the non-afterburning engine in the present drone nacelle with a minimum of changes. A fuel injection device then is needed which not only satisfies the overall requirements of simplicity and economy, but also delivers the pyrophoric fuel in a manner 'which utilizes to the maximum, the qualities this fuel has to offer.

An object of the present invention is to provide a fuel injection device for a pyrophoric fueled thrust augmenter which is simple in construction, lightweight, and inexpensive.

Another object of the present invention is to produce a fuel injection device which can be quickly detached and disassembled for easy cleaning when it is plugged by providing simply constructed tubular nozzles slidably carried in the casing of a turbo-jet engine.

Still another object of the present invention is to provide such a fuel injection device which also radially distributes the fuel to insure maximum afterburner efficiency.

A further object of the present invention is to provide a fuel injection device which will not require the heat liner commonly found in the tailpipe of conventional afterburners and which will enable the length of the tailpipe to be substantially shortened.

' Still a further object of the present invention is to produce a fuel injection device which may be easily installed by providing an assembly which is substantially self alignmg.

Other objects of the present invention will readily occur to those skilled in the art upon reference to the accompanying drawings in which preferred embodiments of the invention are illustrated, and in which like characters refer to like parts throughout the several views and in which FIG. 1 is a perspective View of a structure embodying the present invention.

FIG. 2 is a cross-sectional view taken laterally on the structure shown in FIG. l, and looking downstream in the path of gas flow.

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FIG. 3 is a fragmentary view of FIG. 2 enlarged and somewhat distorted for the purposes of clarity and FIG. 4 is a fragmentary side cross-sectional view of FIG. 2.

A preferred device embodying the present invention is best illustrated in FIG. 1 as including a substantially annular tubular manifold 10. The manifold 10 is provided with an inlet T-fitting 11 adapted to be connected with a fuel supply (not shown). A plurality of straight, heavy walled tubular spray nozzles 12 extend radially i11- wardly from the manifold 10. The tubular spray nozzles 12 are disposed in a plane substantially common to that of the manifold 10.

The nozzles 12 are detachably secured to the manifold 10 so as to provide leakproof communication therewith by any convenient means such as lock iittings 13 welded or otherwise fixed into the manifold 10 and a nut 13A retained on the nozzle 12 by means of a ferrule 12A. The nut 13A is adapted to be threaded onto a threaded portion 13B of the lock fitting 13. Each nozzle 12 has an end portion 16 which is preferably plugged by any convenient means such as welding. Welding has been found to be satisfactory. A plurality of orifices 17 are provided in the nozzles 12. It has been found that if one hole is provided within .060 of the plug at the end of the nozzle 12 formation of oxides is effectively prevented.

The manifold 10 circumferentially encompasses a tailpipe casing 14 and is disposed in a plane substantially normal to the longitudinal axis of the casing 14. The manifold 10 is sufficiently close to the casing 14 to allow the insertion of the nozzles 12 through annularly spaced holes 18 in the casing 14. The insertion is sufficiently deep to fix the orifices 17 of the nozzles 12 inside the tailpipe casing 14. The nozzles 12 are slidably secured to the tailpipe casing 14 by sandwich fittings 15 bolted or otherwise secured to the tailpipe casing 14.

The sandwich fittings 15, as best illustrated in FIGS. 3 and 4 have an inner ilange plate 19 which carries a hollow cylindrical bushing 20 extending outwardly through the casing 14. Holes 18 are provided in the casing 14 and are somewhat larger in diameter than the cylindrical bushing 20 as can be seen in FIGS. 3 and 4. The cylindrical bushing portion 20 provides sliding engagement with the nozzles 12.

Outer flange plate 21 is provided with a hole 22 substantially equal in size to the holes 18. The cylindrical portion 20 is preferably welded to the inner flange plate 19 as at 19A. A V-shaped trough portion 24 of the inner flange plate 19 extends inwardly of the casing 14 closely adjacent to the nozzles 12. Securing elements such as bolts 23 are inserted in aligning holes 23A and are used to sandwich the casing 14 between the outer ilange plate 21 and the inner ilange plate 19. It will be noted in FIG. 4 that the aligning holes 23A are somewhat larger than the Shanks of the bolts 23. This relationship permits the nozzles 12 and manifold 10 to be easily installed in the casing 14.

Because pyrophoric fuels ignite upon Vcontact with air, it is necessary to purge the fuel lines and injection device prior to passage of fuel through them. If the air is not all removed, oxide deposits will form, plugging the lines. Any fuel system utilizing pyrophoric fuels then must be constructed so as to be easily disassembled for cleaning. The present invention possesses this feature. The nozzles 12 are easily detachable from the manifold 10 and the casing 14 since all that is required is the loosening of the nut 13 and an inward pull on the nozzle 12. When the system has been purged, fuel is allowed into the lines, entering the manifold 10 through the inlet fitting 11. The manifold 10 distributes the fuel substantially equally to each of the nozzles 12. The fuel then will be emitted from the orifices 17 where upon contact with air, it will ignite. The trough portions 24 act to stabilize the resulting fiame. The flame will create heat which augments the thrust produced by the main portionV of the engine.

The sandwich fitting 15 provides a means for securing the manifold with respect to the casing'14 without actually fastening it or the nozzles 12 to any part of the casing. The nozzles 12, by reason ofV being annularly spaced, act as radial pins which position the manifold 10 much like spokes positioning the rim of a wheel. All displacement of the manifold. 10 is prevented by preventing movement of the nozzles 12. The sliding engagement provided by the cylindrical bushing 20 does not permit the nozzles 12 to move while they are secured to the manifold 10. The sliding movement of each nozzle 12 is prevented by the inability of other nozzles 12 to move in the direction required to permit such movement. At the same time the sliding radial pin support permits differential expansion between the casing 10 and the manifold 14 without creating undue stress.

The preferred annular configuration ofthe fuel injection device has been found to produce maximum afterburner efficiency by reason of the radial fuel-air distribution it provides. Further, the distribution creates a cold air layer which flows along the inside surface of the tailpipe casing 14. This layer together with the short length of time required to burn pyrophoric fuel enables the afterburner to be built Without a heat liner for the tailpipe, making it much less, expensive than conventional type afterburners. Further, by reason of instantaneous combustion of pyrophoric fuels, the tail pipe length can be shortened.

Testing indicates that the number of nozzles 12 required to produce the most efficient results depends upon the inside diameter of the tailpipe casing 14. Satisfactory results are achieved with an afterburner casing with a diameter of 15" when 10 nozzles are used, each provided with six .025 fuel injection orifices drilled in three pairs.

Although we have described only a few embodiments -of our invention, it will be apparent to one Skilled in the art to which the invention pertains that various changes and modifications may be made therein without departing from the spirit of the invention or the scope of the appended claims.

We claim:

1. In combination with a jet engine afterburner having a substantially annular casing, a fuel injection device comprising (a) a substantially annular manifold structure,

(b) a plurality of substantially straight tubular spray nozzles each extending radially inwardly from said manifold and through holes provided in said casing,

(c) each of said nozzles being removably secured to said manifold members, and

(d) positioning meansv secured to said casing and re-r ceiving said spray nozzles,

(e) each of said spray nozzles being axially slidably carried by said positioning means and said positioning means including means limiting movement of each of said spray nozzles angularly with respect to the axis thereof Without limiting axial movement thereof whereby said manifold member is positioned substantially concentric to said casing and said manifold member may be removed by detaching each of said nozzles from said manifold member and sliding each of said nozzles radially inwardly.

2. In combination with a substantially annular casing defining a combustion chamber a fuel injection device comprising (a) a substantially annular tubular manifold member,

(b) a plurality of substantially straight tubular spray nozzles each extending radially inwardly from said manifold member and through holes provided in said casing,

(c) each of said spray nozzles communicating with said manifold member and being removably secured thereto, and

(d) flange means secured to said casing and axially slidably receiving said spray nozzles,

(e) said iiange means including a portion substantially preventing angular movement of said spray nozzle with respect to the axis thereof without preventing axial movement thereof whereby said manifold member is retained by said spray nozzles in a position substantially concentric to said casing and said manifold member may be removed by detaching each of said spray nozzles from said manifold member and sliding each of said spray nozzles radially inwardly with respect to said manifold member.

3. The combination as defined in claim 2 and including fuel emitting orifices provided in said spray nozzles to emit fuel into said combustion chamber and said flange means including a portion extending radially inwardly `into said combustion chamber in a position closely adjacent each of said spray nozzles whereby to stabilize the lflame produced in said combustion chamber.

, 4. A fuel injection device for injecting fuel into a combustion chamber defined by a substantially annular casing said device comprising (a) an annular tubular manifold member disposed exteriorly of said combustion chamber and substantially concentric to said casing,

(b) a plurality of tubular spray nozzles each extending radially inwardly from said manifold member, through holes provided in said casing and having an end portion disposed in said combustion chamber,

(c) each of said spray nozzles communicating with said manifold member and being removably secured thereto,

(d) flange means secured to said casing and each receiving one of said spray nozzles,

(e) saidv flange means each comprising a fiange element having a cylindrical bushing portion extending through one of the holes provided in'said casing and spaced from the sides of said hole,

(f) said bushing axially slidably receiving one of said spray nozzles whereby to permit said spray nozzle to freely move axially with respect to said bushing but to prevent movement of said spray nozzle angularly with respect to the axis of Said bushing.

5. The device as defined in claim 4 and in which said flange element includes a flame stabilizing portion extending radially inwardly into said combustion chamber closely adjacent said spray nozzle.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN COMBINATION WITH A JET ENGINE AFTERBURNER HAVING A SUBSTANTIALLY ANNULAR CASING, A FUEL INJECTION DEVICE COMPRISING (A) A SUBSTANTIALLY ANNULAR MANIFOLD STRUCTURE, (B) A PLURALITY OF SUBSTANTIALLY STRAIGHT TUBULAR SPRAY NOZZLES EACH EXTENDING RADIALLY INWARDLY FROM SAID MANIFOLD AND THROUGH HOLES PROVIDED IN SAID CASING, (C) EACH OF SAID NOZZLES BEING REMOVABLY SECURED TO SAID MANIFOLD MEMBERS, AND (D) POSITIONING MEANS SECURED TO SAID CASING AND RECEIVING SAID SPRAY NOZZLES, 